Physiological Factors of Exercise Intolerance in Patients With Pectus Excavatum: A Retrospective, Single-Center Study.

INTRODUCTION: Pectus excavatum (PE) causes a sunken thoracic wall, which is associated with adolescent exercise intolerance. Since the underlying physiological factors remain uncertain, this retrospective chart review addressed this knowledge gap by reviewing cardiopulmonary exercise tests (CPETs) and identifying physiological factors of exercise intolerance. METHODS: With the Nemours Institutional Review Board's approval (IRB approval number: STUDY00000806), this study enrolled patients with PE who underwent CPET and chest magnetic resonance imaging (MRI) for Haller index at the Nemours Children's Hospital, Orlando, Florida, from January 2025 to January 2026. Inclusion criteria included age between 12 and 18 years, Haller index greater than 3.25, and completed CPET. Statistical analysis involved paired-sample parametric tests with Benjamini-Hochberg False Discovery Rate (FDR) adjustment and Spearman's rank correlation. RESULTS: Twenty-seven patients (23 male, age 14.9 ± 1.8 years) were enrolled. The mean Haller index was 5.8 ± 3.6. Patients with PE demonstrated significantly lower peak oxygen uptake (VO2), oxygen pulse, and anaerobic threshold compared to expected values derived from pediatric ramp-cycle equations. Patients' average transcutaneous partial pressure of carbon dioxide (PtcCO2) and dead space to tidal volume ratio (VD/VT) at peak exercise were higher than the normative population values. Oxygen pulse had the strongest inverse association with Haller Index, but this was not statistically significant following FDR adjustments (95% CI: -0.674, -0.018; FDR p = 0.372). CONCLUSION: Exercise limitation in patients with PE was corroborated by low peak VO2. This could be explained by a significantly lower oxygen pulse at peak exercise. Future studies should examine these findings in prospective trials.